Chapter 23 - Antiarrhythmic agents

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an abnormality in the rate, regularity, or site of origin of the cardiac impulse or a disruption in impulse conduction such that the normal sequence of atrial and ventricular activation is changed

What are arrhythmias associated with?

the imbalance of the parasympathetic and sympathetic branches of the ANS; changes in serum electrolyte concentrations (K+ and Ca++); hypoxemia; acidosis; changes in concentration of carbon dioxide; excessive stretch of cardiac tissue; mechanical trauma; myocardial disease states (CHF and viral myocarditis); numerous drugs; ischemia and infarction of the heart muscle

What are Class I drugs?

local anesthetic agents and membrane stabilizers

How can Class I drugs control arrhythmias?

by enhanced automaticity

What is the original and prototypical Class I drug?

quinidine

What are Class II drugs?

B-blockers

What do Class III drugs produce?

a prominent prolongation of the action potential, thereby extending the refractory period